1. Field of the Invention
The present invention relates to an auditing system that can record job history information (e.g., execution user, execution date and time, etc.) relating to a scan job, a copy job, or a print job having been executed by a digital multifunction peripheral.
2. Description of the Related Art
Due to recent developments in the techniques relating to various image forming apparatuses, such as printers and digital multifunction peripherals, it becomes easier for many users to print, copy, and transmit an original (i.e., a document to be processed). On the other hand, the improvements in usability have caused new problems, such as information leakage by the print, copy, and transmission of a confidential original (i.e., a confidential document).
To solve this problem, there is a conventional image forming apparatus that can store job history information in a storage device when the apparatus executes a print job, a copy job, a FAX job, or an electronic mail sending job.
For example, the job history information includes job executed user information, job executed date and time information, job executed digital multifunction peripheral information (e.g., IP address, serial number, etc.), and log attribute information indicating the type of an executed job. Further, the job history information may include image data of an input image and reduced image data of the image data.
The auditing system includes a job history information auditing server in addition to the above-described image forming apparatus. The job history information auditing server includes an image processing server, a data server, and a search server. The image processing server, the data server, and the search server can be arbitrarily combined and constructed on different information processing apparatuses (PCs) or can be constructed on the same PC.
The job history information recorded by the image forming apparatus is transmitted to the image processing server and stored in a database constructed on the data server. The job history information can be stored in the database for a predetermined period. The search server can search for job history information stored in the database based on search conditions designated by a user, and can notify a user of a search result. Thus, the auditing system can trace job history information in the event of the occurrence of any leakage of information.
The above-described image forming apparatus and the auditing system require a large-capacity storage area to store job history information of numerous jobs. To this end, there is a conventional method capable of reducing a required storage capacity to realize effective storage of a large amount of job history data.
For example, as discussed in Japanese Patent Application Laid-Open No. 2007-166178, the data amount to be stored in a database can be reduced beforehand by reducing the resolution of image data, selecting a part of image data, or reducing the number of colors of image data when the job history information is stored.
In particular, the selection of image data can be realized by selecting image data of page designation pages or randomly designated pages. Extracting and storing a part of the image data input during the execution of a job, as described above, is referred to as “page filtering” in the following description.
Preventing the leakage of information is one of the main purposes when users introduce the auditing system. To attain the goal, storing the image data of all pages is not essentially required and it will be sufficient if any unfair conduct can be detected by effectively performing sampling in the page filtering processing.
In a conventionally used auditing system, it is feasible to store image data of designated pages only. However, if the sampling is performed based on the regularity of a specific page or a specific number of pages, it may be difficult to obtain an appropriate result in the sampling. For example, a malicious user can execute a job in such a way as to leave nothing about the job history information, by using job data including confidential information as a page other than the specific page or the specific number of pages.
Further, when image data of randomly designated pages is stored, the number of extractable pages is fixed regardless of the size or the volume of a document. For example, even when the document is composed of 100 pages (or 1000 pages), image data of only 50 pages is randomly extracted and stored. Thus, according to this method, if a malicious user executes a job by embedding a small amount of confidential information somewhere in a large number of pages, the acquired job history information may not include any information usable to detect an information leakage. In this respect, the effect of suppressing the information leakage deteriorates significantly and the sampling may not obtain an appropriate result.
Further, when the page filtering processing is performed by the job history information auditing server, the network load may increase excessively because image data of a page not finally stored by the page filtering processing is also transmitted by the digital multifunction peripheral.